### 3D domain decomposition method coupling conforming and nonconforming finite elements

This paper deals with the solution of problems involving partial differential equations in ${\mathbb{R}}^{3}$. For three dimensional case, methods are useful if they require neither domain boundary regularity nor regularity for the exact solution of the problem. A new domain decomposition method is therefore presented which uses low degree finite elements. The numerical approximation of the solution is easy, and optimal error bounds are obtained according to suitable norms.